I believe that drag is a function of the surface area of either the front or rear (or maybe both) trailing edges of the blade.
Which if you look at the ratio of blade area to frontal or trailing edge area, the conventional long thin blades have a horrible ratio.
Those blades are operating in a wind-speed regime that far exceeds the design profile of capturing low-speed terrestrial wind currents. So again I don't know why airplane propeller blades (or in general the long, thin blades) are being thought of as the most optimal to capture energy from 5 to 25 mph wind currents.
Look at the cross-sectional area of a jet turbine. Lots of surface area there. Ever sit on a jet parked at the gate and watch it's turbine rotate as it catches the calm breeze wafting by?
I think that in the future your going to see more of these helical-based turbines:
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"Helical structured wind turbines are the future of wind mill technology. These amazingly unique looking twists and turns will replace those long and boring blades which represent the conventional image of a windmill. These new and sleek looking windmills are designed much like the old ones when it comes to converting their circular motion in to mechanical work, but it is the structural design that makes them unique and special. In fact, they logically should function better than the traditional windmills as the helical structures seems to not just utilize the energy of the wind, but maximize it by containing the wind."
There is still loss even in recycling. First _all_ of a recyclable is never recoved. I suspect iron and copper probably get the highest percentage back while stuff like aluminum and plastic are a low percentage return. Second, even whil processing there is loss.
And water power. Here in Wa state the power companies must by law include a certain percentage of 'renewable power'. But water power is specifically exempted.
What I found shows an 8% drop in harvested acres between 1978 and 2007, although the total acres peaked temporarily in the '90s. _BUT_, the total US sweet corn production acreage is 90M A range or nearly a 100:1 ratio. Sweet corn is simply noise in the overall corn production market.
Also, if one looks at actual production instead of just acres, the fresh corn US production has doubled since 1978 from 14,000 to 28,000 and has continued to rise since 1990.
Sweet corn for production has also actually increased significantly despite the acreage drop; from roughly 2.5M T to 3.24M T in 2009. The increase has been continual w/ only a few yearly fluctuations that represent weather and other crop conditions, primarily, I'm certain.
So, worrying about ethanol diverting needed sweet corn acreage to feed/field corn production just isn't borne out by the data. While there might be some acres lost (altho I suspect the bulk of those aren't owing to switching to field corn but to things like urban expansion, other truck crops, etc. because the commodity grain producers don't do perishable crops in general), increased yields have more than made up for that.
Hmmm....that raises a question...I don't even know how sweet corn (canning, processing, freezing, etc.) is priced. Let's see--oh, ok, it's on a $/T basis, not $/bu. as field corn.
Wow!!!! Those are average of about $100/T --> $2.80/bu (corn is 56 lb/bu; wheat is 60). So, there's even more ammunition about the runup in corn not being real for consumer food prices--they're paying only a third of the bandied corn market price. While that's increased over the years it's only about 20% last year (annual average) as compare to 2007. It's really true in spades for those guys that the producer gets the short end of the stick for the commodity; the processor/retailer is the one making the money. I'll leave on that note--in the early 1990s farm fraction of food dollar was in the 24-27% range, it's now down to under
20%. Complain to somebody in the system other than the producer about the food cost.
Have you seen the eight bladed props on the Airbus A400M Military transport plane? The propellers look quite a bit different from what you'd expect to see on a turboprop engine. I remember seeing pictures of NASA developing such a prop years ago.
It does say that. I drive by the panels frequently, they sure look like the are rigidly mounted...
Yes, that's the one issue I saw with their setup. I thought they'd put down mulch or something. Maybe if they're motorized they'll just move them perpendicular and then be able to run a mower down the lanes.
On 7/21/2011 1:29 PM, snipped-for-privacy@rochester.rr.com wrote: ...
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None I've seen were actually flat, though. All ours had a curve built into the blades; steeper front attack angle than rear. Dated from roughly 1910 on thru the 20's...
The old Delco Windcharger (mid-1910s when ours installed; not sure when they were actually introduced) did have a three-bladed hub; not quite so aerodynamic as current but certainly reminiscent.
See the other posting...note that if all the sweet corn production went to field corn it would only be a blip in the total acres planted that would be well within the statistical uncertainty of total acres planted (650,000 out of some 92,000,000 is
No individual bins here but we do have a central one in town. The problem is that people can't read apparently. "plastic milk jugs only" seems to mean "thow anything at all in here, stupid".
Looks like you are replying to me, but you must mean someone else. I live in the garden spot of the US, central NJ.
Actually, it's amazingly beautiful here, but don't tell anyone.
As for my car, it goes for years at a time without being washed. A good rain gets it clean enough for me.
Our main issue here is tree sap and pollen. Bell Labs doesn't have the 150ft monsters (Tulip Poplars) on it's front lawn like the rest of the town. I'm sure their cleaning issue will be minor.
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